Fixed #29500 -- Fixed SQLite function crashes on null values.

Co-authored-by: Srinivas Reddy Thatiparthy <thatiparthysreenivas@gmail.com>
Co-authored-by: Nick Pope <nick.pope@flightdataservices.com>

django/db/backends/oracle/operations.py

@@ -569,7 +569,7 @@ END;
         if internal_type == 'DateField':
             lhs_sql, lhs_params = lhs
             rhs_sql, rhs_params = rhs
-            return "NUMTODSINTERVAL(%s - %s, 'DAY')" % (lhs_sql, rhs_sql), lhs_params + rhs_params
+            return "NUMTODSINTERVAL(TO_NUMBER(%s - %s), 'DAY')" % (lhs_sql, rhs_sql), lhs_params + rhs_params
         return super().subtract_temporals(internal_type, lhs, rhs)
 
     def bulk_batch_size(self, fields, objs):

django/db/backends/sqlite3/base.py

@@ -3,6 +3,7 @@ SQLite3 backend for the sqlite3 module in the standard library.
 """
 import datetime
 import decimal
+import functools
 import math
 import operator
 import re
@@ -34,6 +35,19 @@ def decoder(conv_func):
     return lambda s: conv_func(s.decode())
 
 
+def none_guard(func):
+    """
+    Decorator that returns None if any of the arguments to the decorated
+    function are None. Many SQL functions return NULL if any of their arguments
+    are NULL. This decorator simplifies the implementation of this for the
+    custom functions registered below.
+    """
+    @functools.wraps(func)
+    def wrapper(*args, **kwargs):
+        return None if None in args else func(*args, **kwargs)
+    return wrapper
+
+
 Database.register_converter("bool", b'1'.__eq__)
 Database.register_converter("time", decoder(parse_time))
 Database.register_converter("datetime", decoder(parse_datetime))
@@ -171,30 +185,30 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         conn.create_function("django_time_trunc", 2, _sqlite_time_trunc)
         conn.create_function("django_time_diff", 2, _sqlite_time_diff)
         conn.create_function("django_timestamp_diff", 2, _sqlite_timestamp_diff)
-        conn.create_function("regexp", 2, _sqlite_regexp)
         conn.create_function("django_format_dtdelta", 3, _sqlite_format_dtdelta)
+        conn.create_function('regexp', 2, _sqlite_regexp)
+        conn.create_function('ACOS', 1, none_guard(math.acos))
+        conn.create_function('ASIN', 1, none_guard(math.asin))
+        conn.create_function('ATAN', 1, none_guard(math.atan))
+        conn.create_function('ATAN2', 2, none_guard(math.atan2))
+        conn.create_function('CEILING', 1, none_guard(math.ceil))
+        conn.create_function('COS', 1, none_guard(math.cos))
+        conn.create_function('COT', 1, none_guard(lambda x: 1 / math.tan(x)))
+        conn.create_function('DEGREES', 1, none_guard(math.degrees))
+        conn.create_function('EXP', 1, none_guard(math.exp))
+        conn.create_function('FLOOR', 1, none_guard(math.floor))
+        conn.create_function('LN', 1, none_guard(math.log))
+        conn.create_function('LOG', 2, none_guard(lambda x, y: math.log(y, x)))
         conn.create_function('LPAD', 3, _sqlite_lpad)
-        conn.create_function('REPEAT', 2, operator.mul)
-        conn.create_function('RPAD', 3, _sqlite_rpad)
-        conn.create_function('ACOS', 1, math.acos)
-        conn.create_function('ASIN', 1, math.asin)
-        conn.create_function('ATAN', 1, math.atan)
-        conn.create_function('ATAN2', 2, math.atan2)
-        conn.create_function('CEILING', 1, math.ceil)
-        conn.create_function('COS', 1, math.cos)
-        conn.create_function('COT', 1, lambda x: 1 / math.tan(x))
-        conn.create_function('DEGREES', 1, math.degrees)
-        conn.create_function('EXP', 1, math.exp)
-        conn.create_function('FLOOR', 1, math.floor)
-        conn.create_function('LN', 1, math.log)
-        conn.create_function('LOG', 2, lambda x, y: math.log(y, x))
-        conn.create_function('MOD', 2, math.fmod)
+        conn.create_function('MOD', 2, none_guard(math.fmod))
         conn.create_function('PI', 0, lambda: math.pi)
-        conn.create_function('POWER', 2, operator.pow)
-        conn.create_function('RADIANS', 1, math.radians)
-        conn.create_function('SIN', 1, math.sin)
-        conn.create_function('SQRT', 1, math.sqrt)
-        conn.create_function('TAN', 1, math.tan)
+        conn.create_function('POWER', 2, none_guard(operator.pow))
+        conn.create_function('RADIANS', 1, none_guard(math.radians))
+        conn.create_function('REPEAT', 2, none_guard(operator.mul))
+        conn.create_function('RPAD', 3, _sqlite_rpad)
+        conn.create_function('SIN', 1, none_guard(math.sin))
+        conn.create_function('SQRT', 1, none_guard(math.sqrt))
+        conn.create_function('TAN', 1, none_guard(math.tan))
         conn.execute('PRAGMA foreign_keys = ON')
         return conn
 
@@ -356,6 +370,8 @@ def _sqlite_date_trunc(lookup_type, dt):
 
 
 def _sqlite_time_trunc(lookup_type, dt):
+    if dt is None:
+        return None
     try:
         dt = backend_utils.typecast_time(dt)
     except (ValueError, TypeError):
@@ -432,6 +448,7 @@ def _sqlite_time_extract(lookup_type, dt):
     return getattr(dt, lookup_type)
 
 
+@none_guard
 def _sqlite_format_dtdelta(conn, lhs, rhs):
     """
     LHS and RHS can be either:
@@ -452,6 +469,7 @@ def _sqlite_format_dtdelta(conn, lhs, rhs):
     return str(out)
 
 
+@none_guard
 def _sqlite_time_diff(lhs, rhs):
     left = backend_utils.typecast_time(lhs)
     right = backend_utils.typecast_time(rhs)
@@ -467,21 +485,25 @@ def _sqlite_time_diff(lhs, rhs):
     )
 
 
+@none_guard
 def _sqlite_timestamp_diff(lhs, rhs):
     left = backend_utils.typecast_timestamp(lhs)
     right = backend_utils.typecast_timestamp(rhs)
     return duration_microseconds(left - right)
 
 
+@none_guard
 def _sqlite_regexp(re_pattern, re_string):
-    return bool(re.search(re_pattern, str(re_string))) if re_string is not None else False
+    return bool(re.search(re_pattern, str(re_string)))
 
 
+@none_guard
 def _sqlite_lpad(text, length, fill_text):
     if len(text) >= length:
         return text[:length]
     return (fill_text * length)[:length - len(text)] + text
 
 
+@none_guard
 def _sqlite_rpad(text, length, fill_text):
     return (text + fill_text * length)[:length]

django/db/models/functions/datetime.py

@@ -218,16 +218,20 @@ class TruncBase(TimezoneMixin, Transform):
 
     def convert_value(self, value, expression, connection):
         if isinstance(self.output_field, DateTimeField):
-            if settings.USE_TZ:
-                if value is None:
-                    raise ValueError(
-                        "Database returned an invalid datetime value. "
-                        "Are time zone definitions for your database installed?"
-                    )
+            if not settings.USE_TZ:
+                pass
+            elif value is not None:
                 value = value.replace(tzinfo=None)
                 value = timezone.make_aware(value, self.tzinfo)
+            elif not connection.features.has_zoneinfo_database:
+                raise ValueError(
+                    'Database returned an invalid datetime value. Are time '
+                    'zone definitions for your database installed?'
+                )
         elif isinstance(value, datetime):
-            if isinstance(self.output_field, DateField):
+            if value is None:
+                pass
+            elif isinstance(self.output_field, DateField):
                 value = value.date()
             elif isinstance(self.output_field, TimeField):
                 value = value.time()

django/db/models/functions/text.py

@@ -139,7 +139,7 @@ class LPad(BytesToCharFieldConversionMixin, Func):
     function = 'LPAD'
 
     def __init__(self, expression, length, fill_text=Value(' '), **extra):
-        if not hasattr(length, 'resolve_expression') and length < 0:
+        if not hasattr(length, 'resolve_expression') and length is not None and length < 0:
             raise ValueError("'length' must be greater or equal to 0.")
         super().__init__(expression, length, fill_text, **extra)
 
@@ -165,13 +165,14 @@ class Repeat(BytesToCharFieldConversionMixin, Func):
     function = 'REPEAT'
 
     def __init__(self, expression, number, **extra):
-        if not hasattr(number, 'resolve_expression') and number < 0:
+        if not hasattr(number, 'resolve_expression') and number is not None and number < 0:
             raise ValueError("'number' must be greater or equal to 0.")
         super().__init__(expression, number, **extra)
 
     def as_oracle(self, compiler, connection, **extra_context):
         expression, number = self.source_expressions
-        rpad = RPad(expression, Length(expression) * number, expression)
+        length = None if number is None else Length(expression) * number
+        rpad = RPad(expression, length, expression)
         return rpad.as_sql(compiler, connection, **extra_context)
 
 

tests/backends/sqlite/tests.py

@@ -59,6 +59,22 @@ class Tests(TestCase):
         creation = DatabaseWrapper(settings_dict).creation
         self.assertEqual(creation._get_test_db_name(), creation.connection.settings_dict['TEST']['NAME'])
 
+    def test_regexp_function(self):
+        tests = (
+            ('test', r'[0-9]+', False),
+            ('test', r'[a-z]+', True),
+            ('test', None, None),
+            (None, r'[a-z]+', None),
+            (None, None, None),
+        )
+        for string, pattern, expected in tests:
+            with self.subTest((string, pattern)):
+                with connection.cursor() as cursor:
+                    cursor.execute('SELECT %s REGEXP %s', [string, pattern])
+                    value = cursor.fetchone()[0]
+                value = bool(value) if value in {0, 1} else value
+                self.assertIs(value, expected)
+
 
 @unittest.skipUnless(connection.vendor == 'sqlite', 'SQLite tests')
 @isolate_apps('backends')

tests/db_functions/datetime/test_extract_trunc.py

@@ -66,11 +66,14 @@ class DateFunctionTests(TestCase):
 
     def create_model(self, start_datetime, end_datetime):
         return DTModel.objects.create(
-            name=start_datetime.isoformat(),
-            start_datetime=start_datetime, end_datetime=end_datetime,
-            start_date=start_datetime.date(), end_date=end_datetime.date(),
-            start_time=start_datetime.time(), end_time=end_datetime.time(),
-            duration=(end_datetime - start_datetime),
+            name=start_datetime.isoformat() if start_datetime else 'None',
+            start_datetime=start_datetime,
+            end_datetime=end_datetime,
+            start_date=start_datetime.date() if start_datetime else None,
+            end_date=end_datetime.date() if end_datetime else None,
+            start_time=start_datetime.time() if start_datetime else None,
+            end_time=end_datetime.time() if end_datetime else None,
+            duration=(end_datetime - start_datetime) if start_datetime and end_datetime else None,
         )
 
     def test_extract_year_exact_lookup(self):
@@ -215,6 +218,12 @@ class DateFunctionTests(TestCase):
         self.assertEqual(DTModel.objects.filter(start_date__month=Extract('start_date', 'month')).count(), 2)
         self.assertEqual(DTModel.objects.filter(start_time__hour=Extract('start_time', 'hour')).count(), 2)
 
+    def test_extract_none(self):
+        self.create_model(None, None)
+        for t in (Extract('start_datetime', 'year'), Extract('start_date', 'year'), Extract('start_time', 'hour')):
+            with self.subTest(t):
+                self.assertIsNone(DTModel.objects.annotate(extracted=t).first().extracted)
+
     @skipUnlessDBFeature('has_native_duration_field')
     def test_extract_duration(self):
         start_datetime = datetime(2015, 6, 15, 14, 30, 50, 321)
@@ -608,6 +617,12 @@ class DateFunctionTests(TestCase):
         qs = DTModel.objects.filter(start_datetime__date=Trunc('start_datetime', 'day', output_field=DateField()))
         self.assertEqual(qs.count(), 2)
 
+    def test_trunc_none(self):
+        self.create_model(None, None)
+        for t in (Trunc('start_datetime', 'year'), Trunc('start_date', 'year'), Trunc('start_time', 'hour')):
+            with self.subTest(t):
+                self.assertIsNone(DTModel.objects.annotate(truncated=t).first().truncated)
+
     def test_trunc_year_func(self):
         start_datetime = datetime(2015, 6, 15, 14, 30, 50, 321)
         end_datetime = truncate_to(datetime(2016, 6, 15, 14, 10, 50, 123), 'year')
@@ -761,6 +776,10 @@ class DateFunctionTests(TestCase):
         with self.assertRaisesMessage(ValueError, "Cannot truncate TimeField 'start_time' to DateField"):
             list(DTModel.objects.annotate(truncated=TruncDate('start_time', output_field=TimeField())))
 
+    def test_trunc_date_none(self):
+        self.create_model(None, None)
+        self.assertIsNone(DTModel.objects.annotate(truncated=TruncDate('start_datetime')).first().truncated)
+
     def test_trunc_time_func(self):
         start_datetime = datetime(2015, 6, 15, 14, 30, 50, 321)
         end_datetime = datetime(2016, 6, 15, 14, 10, 50, 123)
@@ -785,6 +804,10 @@ class DateFunctionTests(TestCase):
         with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to TimeField"):
             list(DTModel.objects.annotate(truncated=TruncTime('start_date', output_field=DateField())))
 
+    def test_trunc_time_none(self):
+        self.create_model(None, None)
+        self.assertIsNone(DTModel.objects.annotate(truncated=TruncTime('start_datetime')).first().truncated)
+
     def test_trunc_day_func(self):
         start_datetime = datetime(2015, 6, 15, 14, 30, 50, 321)
         end_datetime = truncate_to(datetime(2016, 6, 15, 14, 10, 50, 123), 'day')

tests/db_functions/math/test_abs.py

@@ -10,6 +10,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class AbsTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_abs=Abs('normal')).first()
+        self.assertIsNone(obj.null_abs)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-0.8'), n2=Decimal('1.2'))
         obj = DecimalModel.objects.annotate(n1_abs=Abs('n1'), n2_abs=Abs('n2')).first()

tests/db_functions/math/test_acos.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class ACosTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_acos=ACos('normal')).first()
+        self.assertIsNone(obj.null_acos)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-0.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_acos=ACos('n1'), n2_acos=ACos('n2')).first()

tests/db_functions/math/test_asin.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class ASinTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_asin=ASin('normal')).first()
+        self.assertIsNone(obj.null_asin)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('0.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_asin=ASin('n1'), n2_asin=ASin('n2')).first()

tests/db_functions/math/test_atan.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class ATanTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_atan=ATan('normal')).first()
+        self.assertIsNone(obj.null_atan)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_atan=ATan('n1'), n2_atan=ATan('n2')).first()

tests/db_functions/math/test_atan2.py

@@ -9,6 +9,15 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class ATan2Tests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create(big=100)
+        obj = IntegerModel.objects.annotate(
+            null_atan2_sn=ATan2('small', 'normal'),
+            null_atan2_nb=ATan2('normal', 'big'),
+        ).first()
+        self.assertIsNone(obj.null_atan2_sn)
+        self.assertIsNone(obj.null_atan2_nb)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-9.9'), n2=Decimal('4.6'))
         obj = DecimalModel.objects.annotate(n_atan2=ATan2('n1', 'n2')).first()

tests/db_functions/math/test_ceil.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class CeilTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_ceil=Ceil('normal')).first()
+        self.assertIsNone(obj.null_ceil)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_ceil=Ceil('n1'), n2_ceil=Ceil('n2')).first()

tests/db_functions/math/test_cos.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class CosTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_cos=Cos('normal')).first()
+        self.assertIsNone(obj.null_cos)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_cos=Cos('n1'), n2_cos=Cos('n2')).first()

tests/db_functions/math/test_cot.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class CotTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_cot=Cot('normal')).first()
+        self.assertIsNone(obj.null_cot)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_cot=Cot('n1'), n2_cot=Cot('n2')).first()

tests/db_functions/math/test_degrees.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class DegreesTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_degrees=Degrees('normal')).first()
+        self.assertIsNone(obj.null_degrees)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_degrees=Degrees('n1'), n2_degrees=Degrees('n2')).first()

tests/db_functions/math/test_exp.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class ExpTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_exp=Exp('normal')).first()
+        self.assertIsNone(obj.null_exp)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_exp=Exp('n1'), n2_exp=Exp('n2')).first()

tests/db_functions/math/test_floor.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class FloorTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_floor=Floor('normal')).first()
+        self.assertIsNone(obj.null_floor)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_floor=Floor('n1'), n2_floor=Floor('n2')).first()

tests/db_functions/math/test_ln.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class LnTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_ln=Ln('normal')).first()
+        self.assertIsNone(obj.null_ln)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_ln=Ln('n1'), n2_ln=Ln('n2')).first()

tests/db_functions/math/test_log.py

@@ -9,6 +9,15 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class LogTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create(big=100)
+        obj = IntegerModel.objects.annotate(
+            null_log_small=Log('small', 'normal'),
+            null_log_normal=Log('normal', 'big'),
+        ).first()
+        self.assertIsNone(obj.null_log_small)
+        self.assertIsNone(obj.null_log_normal)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('12.9'), n2=Decimal('3.6'))
         obj = DecimalModel.objects.annotate(n_log=Log('n1', 'n2')).first()

tests/db_functions/math/test_mod.py

@@ -9,6 +9,15 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class ModTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create(big=100)
+        obj = IntegerModel.objects.annotate(
+            null_mod_small=Mod('small', 'normal'),
+            null_mod_normal=Mod('normal', 'big'),
+        ).first()
+        self.assertIsNone(obj.null_mod_small)
+        self.assertIsNone(obj.null_mod_normal)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-9.9'), n2=Decimal('4.6'))
         obj = DecimalModel.objects.annotate(n_mod=Mod('n1', 'n2')).first()

tests/db_functions/math/test_power.py

@@ -8,6 +8,15 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class PowerTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create(big=100)
+        obj = IntegerModel.objects.annotate(
+            null_power_small=Power('small', 'normal'),
+            null_power_normal=Power('normal', 'big'),
+        ).first()
+        self.assertIsNone(obj.null_power_small)
+        self.assertIsNone(obj.null_power_normal)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('1.0'), n2=Decimal('-0.6'))
         obj = DecimalModel.objects.annotate(n_power=Power('n1', 'n2')).first()

tests/db_functions/math/test_radians.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class RadiansTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_radians=Radians('normal')).first()
+        self.assertIsNone(obj.null_radians)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_radians=Radians('n1'), n2_radians=Radians('n2')).first()

tests/db_functions/math/test_round.py

@@ -10,6 +10,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class RoundTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_round=Round('normal')).first()
+        self.assertIsNone(obj.null_round)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_round=Round('n1'), n2_round=Round('n2')).first()

tests/db_functions/math/test_sin.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class SinTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_sin=Sin('normal')).first()
+        self.assertIsNone(obj.null_sin)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_sin=Sin('n1'), n2_sin=Sin('n2')).first()

tests/db_functions/math/test_sqrt.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class SqrtTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_sqrt=Sqrt('normal')).first()
+        self.assertIsNone(obj.null_sqrt)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_sqrt=Sqrt('n1'), n2_sqrt=Sqrt('n2')).first()

tests/db_functions/math/test_tan.py

@@ -11,6 +11,11 @@ from ..models import DecimalModel, FloatModel, IntegerModel
 
 class TanTests(TestCase):
 
+    def test_null(self):
+        IntegerModel.objects.create()
+        obj = IntegerModel.objects.annotate(null_tan=Tan('normal')).first()
+        self.assertIsNone(obj.null_tan)
+
     def test_decimal(self):
         DecimalModel.objects.create(n1=Decimal('-12.9'), n2=Decimal('0.6'))
         obj = DecimalModel.objects.annotate(n1_tan=Tan('n1'), n2_tan=Tan('n2')).first()

tests/db_functions/text/test_pad.py

@@ -1,3 +1,4 @@
+from django.db import connection
 from django.db.models import CharField, Value
 from django.db.models.functions import Length, LPad, RPad
 from django.test import TestCase
@@ -8,6 +9,7 @@ from ..models import Author
 class PadTests(TestCase):
     def test_pad(self):
         Author.objects.create(name='John', alias='j')
+        none_value = '' if connection.features.interprets_empty_strings_as_nulls else None
         tests = (
             (LPad('name', 7, Value('xy')), 'xyxJohn'),
             (RPad('name', 7, Value('xy')), 'Johnxyx'),
@@ -21,6 +23,10 @@ class PadTests(TestCase):
             (RPad('name', 2), 'Jo'),
             (LPad('name', 0), ''),
             (RPad('name', 0), ''),
+            (LPad('name', None), none_value),
+            (RPad('name', None), none_value),
+            (LPad('goes_by', 1), none_value),
+            (RPad('goes_by', 1), none_value),
         )
         for function, padded_name in tests:
             with self.subTest(function=function):

tests/db_functions/text/test_repeat.py

@@ -1,3 +1,4 @@
+from django.db import connection
 from django.db.models import CharField, Value
 from django.db.models.functions import Length, Repeat
 from django.test import TestCase
@@ -8,11 +9,14 @@ from ..models import Author
 class RepeatTests(TestCase):
     def test_basic(self):
         Author.objects.create(name='John', alias='xyz')
+        none_value = '' if connection.features.interprets_empty_strings_as_nulls else None
         tests = (
             (Repeat('name', 0), ''),
             (Repeat('name', 2), 'JohnJohn'),
             (Repeat('name', Length('alias'), output_field=CharField()), 'JohnJohnJohn'),
             (Repeat(Value('x'), 3, output_field=CharField()), 'xxx'),
+            (Repeat('name', None), none_value),
+            (Repeat('goes_by', 1), none_value),
         )
         for function, repeated_text in tests:
             with self.subTest(function=function):

tests/expressions/tests.py

@@ -1249,6 +1249,12 @@ class FTimeDeltaTests(TestCase):
         ]
         self.assertEqual(delta_math, ['e4'])
 
+        queryset = Experiment.objects.annotate(shifted=ExpressionWrapper(
+            F('start') + Value(None, output_field=models.DurationField()),
+            output_field=models.DateTimeField(),
+        ))
+        self.assertIsNone(queryset.first().shifted)
+
     @skipUnlessDBFeature('supports_temporal_subtraction')
     def test_date_subtraction(self):
         queryset = Experiment.objects.annotate(
@@ -1266,6 +1272,18 @@ class FTimeDeltaTests(TestCase):
         less_than_5_days = {e.name for e in queryset.filter(completion_duration__lt=datetime.timedelta(days=5))}
         self.assertEqual(less_than_5_days, {'e0', 'e1', 'e2'})
 
+        queryset = Experiment.objects.annotate(difference=ExpressionWrapper(
+            F('completed') - Value(None, output_field=models.DateField()),
+            output_field=models.DurationField(),
+        ))
+        self.assertIsNone(queryset.first().difference)
+
+        queryset = Experiment.objects.annotate(shifted=ExpressionWrapper(
+            F('completed') - Value(None, output_field=models.DurationField()),
+            output_field=models.DateField(),
+        ))
+        self.assertIsNone(queryset.first().shifted)
+
     @skipUnlessDBFeature('supports_temporal_subtraction')
     def test_time_subtraction(self):
         Time.objects.create(time=datetime.time(12, 30, 15, 2345))
@@ -1280,6 +1298,18 @@ class FTimeDeltaTests(TestCase):
             datetime.timedelta(hours=1, minutes=15, seconds=15, microseconds=2345)
         )
 
+        queryset = Time.objects.annotate(difference=ExpressionWrapper(
+            F('time') - Value(None, output_field=models.TimeField()),
+            output_field=models.DurationField(),
+        ))
+        self.assertIsNone(queryset.first().difference)
+
+        queryset = Time.objects.annotate(shifted=ExpressionWrapper(
+            F('time') - Value(None, output_field=models.DurationField()),
+            output_field=models.TimeField(),
+        ))
+        self.assertIsNone(queryset.first().shifted)
+
     @skipUnlessDBFeature('supports_temporal_subtraction')
     def test_datetime_subtraction(self):
         under_estimate = [
@@ -1292,6 +1322,18 @@ class FTimeDeltaTests(TestCase):
         ]
         self.assertEqual(over_estimate, ['e4'])
 
+        queryset = Experiment.objects.annotate(difference=ExpressionWrapper(
+            F('start') - Value(None, output_field=models.DateTimeField()),
+            output_field=models.DurationField(),
+        ))
+        self.assertIsNone(queryset.first().difference)
+
+        queryset = Experiment.objects.annotate(shifted=ExpressionWrapper(
+            F('start') - Value(None, output_field=models.DurationField()),
+            output_field=models.DateTimeField(),
+        ))
+        self.assertIsNone(queryset.first().shifted)
+
     @skipUnlessDBFeature('supports_temporal_subtraction')
     def test_datetime_subtraction_microseconds(self):
         delta = datetime.timedelta(microseconds=8999999999999999)